This invention relates to magnetic storage devices, and more particularly to a flexible magnetic disk contained in a rigid cartridge having a Bernoulli surface against which the disk is rotated.
Flexible or "floppy" disks are frequently used as a magnetic storage medium because of their portability and low cost. These disks are called "floppy" because they tend to sag away from their center when not otherwise supported. The space between a magnetic disc and the transducer is critical for proper non-contact data recording and pick-up. It has been common practice in the art to flatten and stabilize the floppy disk during the read/write operation by rotating the disk at high speeds in close juxtaposition to a flat plate sometimes called a Bernoulli plate. In this way, an air bearing is formed between the plate and disk such that the gap between the record surface and the plate is held constant. In order for the Bernoulli plate to be effective, however, it is important that the surface of the plate is flat and rigid, especially in the region of the plate where the transducer is employed. For this reason, most applications have fixed the Bernoulli plate completely or partially within the disk drive. Examples of this type of device are shown in U.S. Pat. Nos. 3,947,886 - Hiedecker et al, 4,074,330 - Norton et al, and IBM Technical Disclosure Bulletin, Volume 20, No. 11A, of April 1978. One of the disadvantages of placing the plate within the disk drive is that any imperfection in the plate, such as accumulation of contaminants or warping, will require expensive repair and down time for the entire drive. Another disadvantage is the difficulty of ensuring proper plate to disk registry when the disk cartridge is inserted.
Rotating a magnetic disk in juxtaposition to a surface inside a cartridge is not new in the art. For example, see U.S. Pat. No. 3,772,665 - Hertrich. However, in order to make the cartridge reasonably portable, the size of the cartridge is necessarily restricted. As such, any Bernoulli surface contained within the cartridge must be relatively thin and therefore especially susceptible to warping and deformation. This warping and deformation will distort the plate to disk spacing and hence the critical spacing between the transducer and the disk.